388 HYATT: GENEALOGY OF ACHATINELLHXE. 



These notes are, therefore, preliminary statements written by Pro- 

 fessor Hyatt, and which he expected would be modified by the studies 

 he hoped to perfect while in the Hawaiian Islands. A. G. M.] 



Remarks upon Partulina. 



Sub-series of Partulina semicarinata: The first of the two 

 species in this sub-series, Partulina semicarinata of Lanai, 

 has a uniform light-colored pattern throughout life with 

 lighter colored young. The young and adult stage has a 

 prominent, well-formed ridge or keel that disappears only 

 when near the old aperture. 



In Partulina hayseldeni, also of Lanai, there is a finely 

 colored young like that of P. virgulata, having broad white 

 shoulder band and darker side to the volutions. This pat- 

 tern is common on the full-grown adults of some varieties 

 of Achatinella polita of Molokai and is found in the young of 

 varieties of mighelsiana. The ridge is prominent in the shell 

 but disappears earlier in the last volution. The tendency of 

 P. virgulata to have young with angulated sides until a late 

 stage, and the presence of albinos in which the apex has al- 

 most completely lost its colors, shows that this species belongs 

 with hayseldeni and not with variabilis or any more slender 

 form. 



Partulina semicarinata is a dextral species which stands 

 alone. The apex is acute and the spiral similar to that of 

 typical shells and the general form, aperture, columella and 

 tooth also like typical Partulina, but the shell surface is as 

 smooth as in any Achatinellas ; the spire increases more 

 evenly and rapidly, making a stouter shell, and there is a de- 

 cided keel on the basal volution until a late stage of growth 

 when it suddenly and completely disappears. This keel has 

 not the sub-angularity so often noticed in the young of 

 various species but is a distinct prominent ridge. Both form 

 and ridge are like those of Kauaia until a late age, then the 

 latter disappears, the general aspect, the presence of striation 

 in the young that occurs only on the mature volutions of 

 Kauaia and columella, tooth and aperture are like typical 

 Partulina. 



